Estimating HIV hazard rates from cross-sectional HIV prevalence data.

We propose a method of estimating the HIV hazard rate in a population when only cross-sectional data measuring HIV-prevalence are available. In a cross-sectional study, individuals who test positive are left-censored since we know only that the transition time is smaller than the monitoring time. Individuals who test negative are right-censored since we know only that the transition time is greater than the monitoring time. The transition time is not observed directly. For our method, we assume the hazard rate is well-defined after the time we start screening. We assume further the mortality rates for HIV-positive and HIV-negative individuals are known. The method is illustrated using HIV-prevalence data collected over four years among women in Cape Town, South Africa.